Background
Suppression is associated with binocular
vision
conditions such as amblyopia and strabismus.
Commercial
methods of testing fusion often
only measure central fusion or suppression
at near. The purpose of this pilot study was
to assess a new iPad picture fusion test that
assesses foveal and central fusion at near.
Methods
Participants aged 5 years and older presenting
for eye examination at The Ohio State University
College of Optometry were enrolled. Results
from visual acuity, dry and wet refraction/retinoscopy, stereopsis and cover testing were
recorded from the patient chart. The iPad
picture fusion test, Worth four-dot, Worth type
test with foveal letter targets, and Polarized
four-dot were performed by one examiner
in a randomized order at 40 cm. Testing was
repeated with the anaglyphic filters reversed.
Crosstabulation and McNemar chi-square
analysis were used to compare the results
between fusion testing devices.
Results
Of the fifty participants (mean age = 17.5),
twelve reported suppression and one reported
diplopia. Testability was excellent for all tests
(98% to 100%). There were no significant
differences between tests in reported results
(P ≥ 0.22 for all comparisons). No difference
in reported fusion or suppression status was
observed with change in orientation of the
anaglyphic filters. Six participants reported
foveal suppression alone at near which was
not identified with Worth four-dot at near.
Conclusion
The iPad picture fusion test provided excellent
testability and agreement with commonly
used tests of fusion and allowed testing of
both central and foveal fusion at near. Nearly
half (46%) of participants with suppression
reported foveal suppression, supporting the
importance of testing for foveal suppression.
